photovoltaic based landsman converter with fuzzy logic...
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65 International Journal for Modern Trends in Science and Technology
Photovoltaic Based Landsman Converter with Fuzzy Logic Controller Fed BLDC Motor for Water Pumping Applications
Ulliboina Suribabu1 | K.Venkata Kishore2
1PG Scholar, Department of EEE, NRI Institute of Technology, Pothavarapadu, Krishna Dt, Andhra Pradesh, India. 2Associate Professor, Department of EEE, NRI Institute of Technology, Pothavarapadu, Krishna Dt, Andhra Pradesh,
India.
To Cite this Article Ulliboina Suribabu and K.Venkata Kishore, “Photovoltaic Based Landsman Converter with Fuzzy Logic Controller Fed BLDC Motor for Water Pumping Applications”, International Journal for Modern Trends in Science and Technology, Vol. 03, Issue 06, June 2017, pp. 65-72.
In this paper Fuzzy controller based for single array fed BLDC motor for water pumping applications is
presented. Of the various renewable energy sources, Solar Photovoltaic is one among the cheapest and
widely used. Maximum Power Point Techniques are used to extract the maximum power from a PV module
and the fuzzy based MPPT technique has been found to provide better results for randomly varying
atmospheric conditions as compared to other methods. The primary function of a DC– DC Landsman
converter is to optimize the power output of SPV array and it also provides the safe and soft starting of the
BLDC motor with an appropriate control. Amongst various DC–DC converters, Landsman converter meets the
desired performance of proposed water pumping system. The starting, dynamic and steady-state behaviors
of the SPV array fed BLDC motor driven water pump are presented to demonstrate the novelty of the
proposed system. Induction Motors have been in use for years and now are being replaced by Brushless DC
Motors owing to their advantages. The main advantages are higher efficiency and noiseless operation. The
performance of the drive is analyzed for wide range of operations. Further to add to its features minimal rule
based fuzzy logic speed controller is introduced. The performance characteristics of the proposed drive
system are obtained for different operating conditions. Thetotal system performance can be evaluated by
using MATLAB/SIMULINK software.
Copyright © 2017 International Journal for Modern Trends in Science and Technology
All rights reserved.
I. INTRODUCTION
Nonconventional sources of energy are gaining
attention on account of dwindling fossil fuels.
Using solar energy in coordination with
conventional sources of energy will be more
promising. The drastic reduction in the cost of
power electronic devices and annihilation of fossil
fuels in near future invite to use the solar
photovoltaic (SPV) generated electrical energy for
various applications as far as possible [1]. The
water pumping, a standalone application of the
SPV array generated electricity is receiving wide
attention now a days for irrigation in the fields,
household applications and industrial use.
The BLDC motor has high reliability, high
efficiency, high torque/inertia ratio, improved
cooling, low radio frequency interference and noise
and requires practically no maintenance. To
optimize the operating point of the SPV array in
order to get maximum possible power output by
means of the superior maximum power point
tracking (MPPT) technique. A converter acts as an
ABSTRACT
International Journal for Modern Trends in Science and Technology
Volume: 03, Issue No: 06, June 2017
ISSN: 2455-3778
http://www.ijmtst.com
66 International Journal for Modern Trends in Science and Technology
Ulliboina Suribabu and K.Venkata Kishore : Photovoltaic Based Landsman Converter with Fuzzy Logic Controller Fed BLDC Motor for Water Pumping Applications
interface between the SPV array and Voltage
Source Inverter (VSI) feeding the BLDC motor [2].
The starting inrush current of BLDC motor is
restricted within the permissible range by
appropriate control of Landsman converter
through MPPT algorithm.
Investigating the various non-isolated DC–DC
converters viz. buck, boost, buck–boost, Cuk and
single-ended primary inductor converter for
photovoltaic applications, although not based on
water pumping, it is concluded that the best
selection of DC–DC converter in the PV system is
buck–boost converter, allowing an unbounded
region for MPPT. On the contrary to it, a
buck–boost converter always calls for a ripple filter
at its both input and output for coveted operation
of the overall system, resulting in an associated
circuitry [3-7]. A Landsman converter, one of the
topology of a DC–DC buck–boost converter,
capable to overcome the aforementioned
limitations of various previously used converters in
SPV array fed water pumping, is adapted in this
work. This converter is apparently derived by a
CSC or topological transformations on a DC–DC
boost converter. A small input inductor of the
Landsman converter, as shown in Fig.1, acts as an
input-ripple filter, eliminating the external ripple
filtering. This inductor also damps the oscillation
occurred, due to the snubbed elements of insulated
gate bipolar transistor (IGBT) module, in the
current through the module.
In this paper, fuzzy logic controller (FLC) is used
for the control of the speed of the BLDC motor. The
speed controllers are the conventional PI
controllers and current controllers are the P
controllers to achieve high performance drive.
Fuzzy logic can be considered as a mathematical
theory combining multi-valued logic, probability
theory, and artificial intelligence to simulate the
human approach in the solution of various
problems by using an approximate reasoning to
relate different data sets and to make decisions [8].
The Landsman converter is designed to operate
always in continuous conduction mode (CCM)
irrespective of the variation in irradiance level,
resulting in a reduced stress on its power devices
and components. The speed of BLDC motor is
controlled by variation in the DC-link voltage. No
additionalphase current sensors, additional
control or associated circuitry are imposed unlike
for the speedcontrol [9-13].The motor always
attains the required speed to pump the water
irrespective of the atmospheric variation. By using
fuzzy logic controller for BLDC motor the various
performances of the proposed water pumping
system are analyzed through simulated results in
MATLAB/SIMULINK software.
Fig.1. Configuration of SPV array – Landsman converter fed
BLDC motor driven water pumping system
II. CONFIGURATION AND OPERATION OF
PROPOSED SYSTEM
Fig.1 illustrates the detailed configuration and
operation of the proposed SPV array-based BLDC
motor driven water pumping system using the
Landsman converter. The proposed system
consists of an SPV array, Landsman converter, VSI
and the BLDC motor with a water pump coupled to
its shaft. The Landsman converter, acting as an
interface between the SPV array and the VSI, is
operated by the execution of INC-MPPT algorithm
in order to extract the maximum power available
from the SPV array. The VSI, operated through the
electronic commutation, feeds the BLDC motor
pump. The motor has three inbuilt low-cost
Hall-effect position sensors, generating a particular
combination of three Hall signals according to the
rotor position.
III. OPERATING PRINCIPLE OF LANDSMAN
CONVERTER
The Landsman converter is designed to operate
in CCM irrespective of the variation in irradiance
level. The circuit operation is divided into two
modes as shown in Figs.2a, b, and the associated
waveforms are shown in Fig. 2 c.
Mode I – when switch is ON
When the switch is on, VC1,the voltage across
intermediate capacitor C1 reverse biases the diode,
resulting in a circuit configuration shown in Fig.2a.
The inductor current IL flows through the switch.
Since VC1is larger than the output voltage Vdc, C1
discharges through the switch, transferring energy
to the inductor L and the output. Therefore, Vc1
67 International Journal for Modern Trends in Science and Technology
Ulliboina Suribabu and K.Venkata Kishore : Photovoltaic Based Landsman Converter with Fuzzy Logic Controller Fed BLDC Motor for Water Pumping Applications
decreases and IL increases, as shown in Fig.2c. The
input feeds energy to the input inductor L1.
Mode II – when switch is OFF
When the switch is off, diode is forward biased,
resulting in a circuit configuration as shown in Fig.
2b. The inductor current IL flows through the
diode. The inductor L transfers its stored energy to
output through the diode. On the other hand, C1 is
charged through the diode by energy from both the
input and L1.Therefore, vc1increases and IL
decreases, as shown in Fig.2c.
Current ripple in input inductor L1
The ripple in input current, that is the current
through L1, IL1iscalculated by considering its
waveform as shown in Fig.2c for CCM of operation,
assuming that all of the ripple component
iniL1flows through C1. The shaded area in the
waveform of vc1represents an additional flux ΔΦ.
Therefore, the peak-to-peak current ripple DIL1is
written as
(1)
From Fig.2c during switch off, the current through
C1 is as
(2)
Where D is the duty ratio and T is the switching
period. The voltage ripple content in vc1is
estimated from (2) as
(3)
Therefore, substituting DVC1from (3) into (1) gives
(4)
(a)
(b)
(c)
Fig.2 Operation of the Landsman converter a Mode I b Mode II c
Waveforms
(5)
It is normalized as
(6)
Where fSW = 1/T is the switching frequency. From
the input–output relationship, it is obvious that
(7)
whereIdc is the output current of Landsman
converter
Therefore, substituting IL1from (7) into (5) and
rearranging the terms, it gives
68 International Journal for Modern Trends in Science and Technology
Ulliboina Suribabu and K.Venkata Kishore : Photovoltaic Based Landsman Converter with Fuzzy Logic Controller Fed BLDC Motor for Water Pumping Applications
(8)
IV. DESIGN OF PROPOSED SYSTEM
The configuration of the proposed system
presented in Fig.1 has various stages viz. SPV
array, Landsman converter, BLDC motor and a
water pump. These stages are designed such that
the operation and performances remain
satisfactory and are not deteriorated even by the
sudden atmospheric disturbances. A BLDC motor
is selected to drive a water pump of 5.8 kW.
A. Design of SPV array
To ensure the successful operation even at the
minimum solar irradiance of 200 W/m2 and
considering the losses associated with converters
and motor pump, an SPV array of 6.8 kW peak
power rating is selected and designed for the
proposed system. An array of the required size is
made by using HBL Power System Ltd. make SPV
module, HB-12100 with peak power capacity of
100 W. The maximum voltage of SPV array is
selected as 289 V. The electrical specifications of
HB-12100 and designed SPV array at 1000 W/m2
are estimated in Table.1.
TABLE 1 DESIGN OF SOLAR PV ARRAY
B. Design of Landsman converter
The Landsman converter is designed to operate
in CCM irrespective of the operating conditions.
Following the atmospheric variation, the converter
automatically operates either in buck mode or
boost mode. The estimation of the parameters of
Landsman converter is summarized in Table 3.2,
where C is the output capacitor at the DC link of
VSI, ΔIL is the permitted current ripple in IL, ΔVdc is
the permitted voltage ripple in Vdc, ωh and ωl are
the highest and lowest values of VSI output voltage
frequencies, respectively, in rad/s, f isthe
frequency of VSI output voltage in Hz, Ch and Cl
are the capacitors estimated corresponding to ωh
and ωl, respectively, P is the number of poles in the
BLDC motor, Nrated is the rated speed of the motor
and N is the minimum speed required to pump the
water.
TABLE 2 Design of Landsman Converter
C. Design of water pump
A water pump is coupled to the shaft of BLDC
motor, acting as a load. This pump is designed by
its power–speed characteristics as
(9)
Where Kp is proportionality constant, Pm is the
rated power and ω is the rated speed of selected
BLDC motor.
V. CONTROL OF PROPOSED SYSTEM
There are two control methodologies used in the
proposed system at two different stages, one for
MPPT of SPV array and another for BLDC motor
operation as elaborated in the subsequent
sections.
A. INC-MPP tracking
An INC-MPPT technique is applied to track the
optimum operating point of SPV array. This
technique states that the power slope of the PV
array is null, positive and negative, respectively, at
MPP (dppv/dvpv = 0), left of MPP and right of MPP.
Due to this fact, the MPP can be found in terms of
INC as
(10)
69 International Journal for Modern Trends in Science and Technology
Ulliboina Suribabu and K.Venkata Kishore : Photovoltaic Based Landsman Converter with Fuzzy Logic Controller Fed BLDC Motor for Water Pumping Applications
(11)
(12)
(13)
(14)
To implement the INC-MPPT algorithm, the
direct duty ratio control is adapted in view of the
simplicity. This method obviating the proportional
integral (PI) controller directly uses duty ratio as
the control parameter. The direct duty ratio
perturbation offers very good stability
characteristics and high energy utilization
efficiency due to the low impact of noise and the
absence of oscillation. Moreover, higher
perturbation rates up to the PWM rate can be used
without losing the global stability of the system.
An excellent tracking performance under dynamic
condition with negligible oscillations around
optimum operating point is achieved. Optimally
selecting the initial value of duty ratio and its
perturbation size offer soft starting of BLDC motor
by slowly increasing the DC-link voltage of VSI.
B. Electronic commutation of BLDC motor
An electronic commutation of BLDC motor stands
for commutating the currents flowing through
windings of BLDC motor in a predefined sequence
using a decoder circuit. Three inbuilt low-cost Hall
sensors generate three Hall signals according to
the rotor position at an interval of 60°. These Hall
signals are then converted, using a decoder circuit,
into the six switching pulses tope rate the VSI
feeding a BLDC motor. In this manner,
fundamental frequency switching of VSI is
obtained, resulting in are reduced switching loss.
Table 3 shows the switching states of VSI for each
particular combination of Hall signal states. It is
perceptible that only two switches conduct at a
time, resulting in120° conduction mode of
operation of VSI and hence the reduced conduction
losses.
Table.3. Switching states for electronic commutation of
BLDC motor
VI. MATLAB/SIMULINK RESULTS
Fig.3.MATLAB/SIMULINK circuit of SPV array–Landsman
converter fed BLDC motor drive
Fig4. Simulation model of Speed, PV voltage, PV current and
Power
70 International Journal for Modern Trends in Science and Technology
Ulliboina Suribabu and K.Venkata Kishore : Photovoltaic Based Landsman Converter with Fuzzy Logic Controller Fed BLDC Motor for Water Pumping Applications
Fig.5.Simulation waveform for Load Current 1, Capacitor voltage
1, Load current, Switch voltage, Switch current, Diode voltage,
Diode current, DC voltage
Fig.6.Simulation waveform for Back EMF, Stator current, Speed,
Electromagnetic torque, Load torque
Fig.7.MATLAB/SIMULINK circuit of SPV array–Landsman
converter fed BLDC motor drive
Fig.8.Simulation waveform for Speed, PV voltage, PV current and
Power.
Fig.9. Simulation waveform for Load current 1, Capacitor voltage
1, Load current, Switch voltage, Switch current, Diode voltage,
Diode current and DC current
71 International Journal for Modern Trends in Science and Technology
Ulliboina Suribabu and K.Venkata Kishore : Photovoltaic Based Landsman Converter with Fuzzy Logic Controller Fed BLDC Motor for Water Pumping Applications
Fig.10. Simulation waveform for Back EMF, Stator current,
Speed, Electromagnetic torque and Load torque.
Fig.11.MATLAB/SIMULINK circuit of SPV array–Landsman
converter fed BLDC motor drive with fuzzy logic controller
Fig.12.Simuation waveform for Back EMF, Stator current, Speed,
Electromagnetic torque and Load torque
VII. CONCLUSION
In this paper A solar PV array-based BLDC motor
driven water pump employing Landsman converter
has been proposed, and its starting, dynamic and
steady-state behaviors have been analyzed through
simulation and implementation on the developed
system. The utilization of Landsman converter has
eliminated external filtering requirement and has
also contributed to damp the oscillations occurred
in the module current due to snubber elements.
The speed control of BLDC motor by variable
DC-link voltage has completely eliminated the
additional phase current sensing, DC-link voltage
sensing, additional control and associated
circuitry. The fuzzy logic controller is implemented
to proposed circuit to attain better performance
regarding good speed and reduction of torque
ripples. The Landsman converter with fuzzy based
BLDC motor is hence proved as a compatible and
suitable combination for SPV array-based water
pumping with better speed control. The future
development of the project is hybrid renewable
energy system and hybrid fuzzy logic controller.
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